Wireless power receiving apparatus

1. A control circuit employed for a wireless power receiving apparatus that receives an electric power signal from a wireless power transmission apparatus, the control circuit comprising: an electric power detection unit that detects a received electric power received by the wireless power receiving apparatus; a control unit that generates a control signal for controlling a transmitted electric power to be transmitted from the wireless power transmission apparatus; and an abnormal state judgment unit that judges whether or not an abnormal state has occurred, based on the received electric power detected by the electric power detection unit and a past state of the wireless power receiving apparatus; wherein the abnormal state judgment unit sets a threshold value based on past data of the received electric power detected by the electric power detection unit in a period in which judgment was made that a normal operation was being performed, and wherein the abnormal state judgment unit judges whether or not an abnormal state has occurred, based on a comparison result between the threshold value and the received electric power detected by the electric power detection unit in a current stage.

2. The control circuit according to claim 1 , wherein, when the received electric power detected by the electric power detection unit falls despite the control signal not indicating an instruction to lower the electric power to be transmitted, the abnormal state judgment unit judges that an abnormal state has occurred.

3. The control circuit according to claim 1 , wherein the abnormal state judgment unit sets the threshold value based on past data of the received electric power detected by the electric power detection unit multiple times or otherwise for a predetermined period of time in a period in which judgment was made that a normal operation was being performed.

4. The control circuit according to claim 1 , wherein the abnormal state judgment unit sets the threshold value to a value obtained by subtracting a predetermined allowable difference from the received electric power detected in a normal state.

5. The control circuit according to claim 4 , wherein the allowable difference can be set via an external circuit.

6. The control circuit according to claim 1 , wherein the abnormal state judgment unit calculates an expected value of the received electric power to be received by the wireless power receiving apparatus, and wherein the abnormal state judgment unit judges whether or not an abnormal state has occurred, based on the expected value and the received electric power detected by the electric power detection unit in a current stage.

7. The control circuit according to claim 6 , wherein, when a difference between the received electric power detected by the electric power detection unit in the current stage and the expected value exceeds a predetermined allowable difference, the abnormal state judgment unit judges that an abnormal state has occurred.

8. The control circuit according to claim 1 , further comprising a communication unit that transmits, to the wireless power transmission apparatus, the control signal and data that indicates a detection value of the received electric power, wherein, when the abnormal state judgment unit has judged that an abnormal state has occurred, the communication unit transmits data that instructs the wireless power transmission apparatus to suspend a power supply operation.

9. The control circuit according to claim 1 , further comprising a communication unit that transmits, to the wireless power transmission apparatus, the control signal and data that indicates a detection value of the received electric power, wherein the abnormal state judgment unit is configured to judge, for every first period, whether or not an abnormal state is present, and wherein the communication unit transmits data that indicates a detection value of the received electric power to the wireless power transmission apparatus for every second period, which is longer than the first period.

10. The control circuit according to claim 9 , wherein, when the abnormal state judgment unit judges that an abnormal state has occurred, the communication unit transmits data that indicates a detection value of the received electric power to the wireless power transmission apparatus.

11. The control circuit according to claim 1 , further comprising a communication unit that transmits, to the wireless power transmission apparatus, the control signal and data that indicates a detection value of the received electric power, wherein, when the abnormal state judgment unit judges that an abnormal state has occurred, the communication unit transmits data that instructs the wireless power transmission apparatus to perform foreign object detection.

12. The control circuit according to claim 1 , wherein the control circuit conforms to the Qi standard.

13. The control circuit according to claim 1 , monolithically integrated on a single semiconductor substrate.

14. An electronic device comprising: a reception antenna comprising a reception coil that receives the electric power signal; a rectifier circuit that rectifies a current that flows through the reception coil; a smoothing capacitor that is connected to an output of the rectifier circuit, so as to generate a rectified voltage; and the control circuit according to claim 1 .

15. A method for detecting an abnormal state, which is employed in a wireless power receiving apparatus that receives an electric power signal transmitted from a wireless power transmission apparatus, the method comprising: detecting a received electric power received by the wireless power receiving apparatus; generating a control signal for controlling a transmitted electric power to be transmitted from the wireless power transmission apparatus; judging whether or not an abnormal state has occurred, based on the received electric power thus detected and a state of the wireless power transmission apparatus; setting a threshold value based on past detected data of the received electric power in a period in which judgment was made that a normal operation was being performed; wherein, in the judging, whether or not an abnormal state is present is judged based on a comparison result between the threshold value and the received electric power detected in a current stage.

16. The method according to claim 15 , wherein, in the judging, when the received electric power thus detected falls despite the control signal not indicating an instruction to lower the electric power to be transmitted, judgment is made that an abnormal state has occurred.

17. The method according to claim 15 , further comprising calculating an expected value of the received electric power to be received by the wireless power receiving apparatus, wherein, in the judging, whether or not an abnormal state is present is judged based on the expected value and the received electric power detected in a current stage.

18. The method according to claim 17 , wherein, in the judging, when a difference between the received electric power detected in the current stage and the expected value exceeds a predetermined allowable difference, judgment is made that an abnormal state has occurred.

19. A control circuit employed for a wireless power receiving apparatus that receives an electric power signal from a wireless power transmission apparatus, the control circuit comprising: an electric power detection unit that detects a received electric power received by the wireless power receiving apparatus; a control unit that generates a control signal for controlling a transmitted electric power to be transmitted from the wireless power transmission apparatus; an abnormal state judgment unit that judges whether or not an abnormal state has occurred, based on the received electric power detected by the electric power detection unit and a past state of the wireless power receiving apparatus; and a communication unit that transmits, to the wireless power transmission apparatus, the control signal and data that indicates a detection value of the received electric power, wherein the abnormal state judgment unit is configured to judge, for every first period, whether or not an abnormal state is present, and wherein the communication unit transmits data that indicates a detection value of the received electric power to the wireless power transmission apparatus for every second period, which is longer than the first period.